WO2020194182A1 - Structural bonding tape with epoxide microcapsules - Google Patents

Structural bonding tape with epoxide microcapsules Download PDF

Info

Publication number
WO2020194182A1
WO2020194182A1 PCT/IB2020/052743 IB2020052743W WO2020194182A1 WO 2020194182 A1 WO2020194182 A1 WO 2020194182A1 IB 2020052743 W IB2020052743 W IB 2020052743W WO 2020194182 A1 WO2020194182 A1 WO 2020194182A1
Authority
WO
WIPO (PCT)
Prior art keywords
sensitive adhesive
pressure sensitive
epoxy resin
particles
epoxy
Prior art date
Application number
PCT/IB2020/052743
Other languages
French (fr)
Inventor
Jian Li
Catherine E. BARDEAU
Frank A. Brandys
Kejian Zhang
Weixing HOU
Original Assignee
3M Innovative Properties Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 3M Innovative Properties Company filed Critical 3M Innovative Properties Company
Priority to US17/442,971 priority Critical patent/US20220195247A1/en
Priority to CN202080025545.1A priority patent/CN113646398A/en
Priority to EP20715473.3A priority patent/EP3947582A1/en
Priority to JP2021557545A priority patent/JP2022526958A/en
Publication of WO2020194182A1 publication Critical patent/WO2020194182A1/en

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09JADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00Adhesives in the form of films or foils
    • C09J7/10Adhesives in the form of films or foils without carriers
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09JADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00Additional features of adhesives in the form of films or foils
    • C09J2301/30Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
    • C09J2301/302Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09JADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00Additional features of adhesives in the form of films or foils
    • C09J2301/40Additional features of adhesives in the form of films or foils characterized by the presence of essential components
    • C09J2301/412Additional features of adhesives in the form of films or foils characterized by the presence of essential components presence of microspheres
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09JADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2463/00Presence of epoxy resin

Definitions

  • This disclosure relates to structural bonding tapes including particles of encapsulated epoxy resin blended with epoxy curative and methods and products of their use.
  • PSA Pressure sensitive adhesives
  • PSA Pressure sensitive adhesives
  • Traditional structural bonding tapes offer high adhesion, but typically lack adhesion prior to thermal activation.
  • SBT products may have limited stability and may require cold storage and shipping with dry-ice.
  • the present disclosure provides curable pressure sensitive adhesive tapes comprising: a) a pressure sensitive adhesive polymer; b) particles of encapsulated first epoxy resin (microcapsules) mixed into the pressure sensitive adhesive polymer; and c) a first epoxy curative.
  • the first epoxy curative is blended into the pressure sensitive adhesive.
  • the first epoxy curative is the pressure sensitive adhesive polymer.
  • the first epoxy curative is not encapsulated.
  • the first epoxy curative is selected from polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof.
  • the first epoxy curative may be an adduct of a second epoxy curative and a second epoxy resin in a ratio of at least 2: 1 second epoxy curative to second epoxy resin.
  • the second epoxy curative is selected from polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and
  • the particles of encapsulated first epoxy resin comprise a core of first epoxy resin within a shell comprising an organic polymer.
  • the shell comprises a polymer selected from the group consisting of polyurea, polyurethane, polymethylene urea, cured epoxy resin, and combinations thereof.
  • the particles of encapsulated first epoxy resin may additionally comprise a layer of oil-in-water Pickering emulsifier particles borne on a surface of the shells.
  • the tape may be cured to form a structural bond between adherends.
  • the present disclosure provides methods of affixing substrates, comprising: a) bringing a curable pressure sensitive adhesive tape according to any of the present disclosure into contact with a first substrate; b) bringing the curable pressure sensitive adhesive tape into contact with a second substrate; and c) heating the curable pressure sensitive adhesive tape to a curing temperature, which is a temperature sufficient to activate the particles of encapsulated first epoxy resin and cure the first epoxy resin.
  • the curing temperature may be not more than 200 °C, not more than 170 °C, not more than 110 °C, or not more than 80 °C. Additional embodiments of the method of affixing substrates of the present disclosure are described below under“Selected Embodiments.”
  • the present disclosure provides constructions comprising a first substrate bound to a second substrate by a layer of cured epoxy resin, wherein the layer of cured epoxy resin comprises shells comprising an organic polymer.
  • the shells comprise a polymer selected from the group consisting of polyurea, polyurethane, polymethylene urea, cured epoxy resin, and combinations thereof, and may additionally comprise a layer of oil-in-water Pickering emulsifier particles borne on a surface of the shells. Additional embodiments of the constructions of the present disclosure are described below under“Selected Embodiments.”
  • activated or“activation”, with regard to particles of encapsulated epoxy resin means altered (e.g., by heat or mechanical disruption) so as to allow chemical reaction between the epoxy resin and species external to the particles, and may include without limitation shell rupture, shell wall thinning, shell wall softening, shell wall dissolution, or shell wall permeablization;
  • free-standing film means a film that is solid at normal temperature and pressure and has mechanical integrity independent of contact with any supporting material (which excludes, inter alia , liquids, surface coatings dried or cured in situ such as paints or primers, and surface coatings without independent mechanical integrity);
  • (meth)acrylate includes, separately and collectively, methacrylate and acrylate
  • normal temperature and pressure or“NTP” means a temperature of 20 °C (293.15 K, 68 °F) and an absolute pressure of 1 atm (14.696 psi, 101.325 kPa);
  • oil-in-water Pickering emulsifier particles means particles suitable as
  • Pickering emulsifiers in an oil-in-water emulsion which may have surfaces somewhat more hydrophilic than hydrophobic in character or evenly hydrophilic/hydrophobic in character (which may be reflected in exhibiting a contact angle of the particle surface with water of 50-95° or 60-90°), and which may have an average diameter of 5-1000 nanometers;
  • pressure sensitive adhesive means materials having the following properties: a) aggressive and permanent tack, b) the ability to adhere with no more than finger pressure, c) the ability to adhere without activation by any energy source, d) sufficient ability to hold onto the intended adherend, and preferably e) sufficient cohesive strength to be removed cleanly from the adherend; which materials typically meet the Dahlquist criterion of having a storage modulus at 1 Hz and room temperature of less than 0.3MPa; and “structural adhesive” means an adhesive that binds by irreversible cure, typically with a strength when bound to its intended substrates, measured as stress at break (peak stress) using the overlap shear test described in the Examples herein, of at least 4.14 MPa (600 psi), more typically at least 5.52 MPa (800 psi), in some embodiments at least 6.89 MPa (1000 psi), and in some embodiments at least 8.27 MPa (1200 psi).
  • FIG. 1 schematically depicts a process of forming particles of encapsulated epoxy resin using a Pickering emulsifier.
  • FIGS. 2(a)-(d) are scanning electron micrographs of particles of encapsulated epoxy resin as described in the Examples herein.
  • the present disclosure provides curable pressure sensitive adhesive tapes comprising: a) a pressure sensitive adhesive polymer; b) particles of encapsulated first epoxy resin (microcapsules) mixed into the pressure sensitive adhesive polymer; and c) a first epoxy curative.
  • the first epoxy curative is blended into the pressure sensitive adhesive.
  • the first epoxy curative is the pressure sensitive adhesive polymer.
  • the first epoxy curative is not encapsulated.
  • the tape may be cured to form a structural bond between adherends.
  • the present disclosure also provides particles of encapsulated first epoxy resin (microcapsules) comprising a) a core of first epoxy resin, within b) a shell comprising an organic polymer, and c) a layer of oil-in-water Pickering emulsifier particles borne on an outer surface of the shell.
  • microcapsules comprising a) a core of first epoxy resin, within b) a shell comprising an organic polymer, and c) a layer of oil-in-water Pickering emulsifier particles borne on an outer surface of the shell.
  • These particles may be used in liquid adhesive compositions, in the tapes described above, or in other applications. Since the curable epoxy is sequestered, the particles of encapsulated epoxy resin can be blended with epoxy curative to form one-part epoxy adhesives with long shelf life and high stability, yet which cure to form strong structural bonds.
  • Particles of encapsulated epoxy resin (microcapsules) according to the present disclosure comprise a core of curable epoxy resin enclosed in a shell.
  • the outer surface of the shell may include an emulsifier.
  • Any suitable curable epoxy resin may be used, that is, any suitable organic compound having one or more oxirane rings polymerizable by a ring opening reaction.
  • Suitable curable epoxy resins may include monomeric epoxy compounds and polymeric epoxy compounds and can be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyclic, or can comprise combinations thereof.
  • Useful materials typically have at least two polymerizable epoxy groups per molecule (that is, polyepoxides) and, more preferably, from two to four polymerizable epoxy groups per molecule.
  • the curable epoxy resin is a liquid at NTP.
  • the curable epoxy resin is a solid at NTP.
  • Suitable curable epoxy resins may include the polyglycidyl ethers of polyhydric phenols (for example, bisphenol A derivative resins, epoxy cresol-novolac resins, bisphenol F derivative resins, epoxy phenol -novolac resins), glycidyl esters of aromatic carboxylic acids, glycidyl amines of aromatic amines, and the like, and mixtures thereof.
  • polyhydric phenols for example, bisphenol A derivative resins, epoxy cresol-novolac resins, bisphenol F derivative resins, epoxy phenol -novolac resins
  • glycidyl esters of aromatic carboxylic acids for example, bisphenol A derivative resins, epoxy cresol-novolac resins, bisphenol F derivative resins, epoxy phenol -novolac resins
  • glycidyl esters of aromatic carboxylic acids for example, bisphenol A derivative resins, epoxy cresol-novolac resins, bisphenol F derivative resins, epoxy phenol -novolac resin
  • aliphatic polyepoxides that can be utilized include 3 ',4'-epoxycyclohexylmethyl-3, 4-epoxy cy cl ohexanecarboxylate, 2-(3',4'- epoxy cy cl ohexyl)-5,l "-spiro-3 ",4"-epoxycyclohexane-l,3-dioxane, bis(3,4- epoxycyclohexylmethyl)adipate, the diglycidyl ester of linoleic dimer acid,
  • aromatic polyepoxides that can be utilized include glycidyl esters of aromatic carboxylic acids (for example, phthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, trimellitic acid triglycidyl ester, pyromellitic acid tetraglycidyl ester, and the like, and mixtures thereof); N- glycidylaminobenzenes (for example, N,N-diglycidylbenzeneamine, bis(N,N- diglycidyl-4-aminophenyl)methane, l,3-bis(N,N-diglycidylamino)benzene, N,N- diglycidyl-4-glycidyloxybenzeneamine, and the like, and mixtures thereof); the polyglycidyl derivatives of polyhydric phenols (for example, the polyglycidyl ethers of polyhydric phenols such as 2,2-bis-[4-[4
  • Suitable epoxy resins can be prepared by, for example, the reaction of epichlorohydrin with a polyol, as described, for example, in U.S. Patent No. 4,522,958 (Das et ah), the description of which is incorporated herein by reference, as well as by other methods described by Lee and Neville and by May, supra. Many epoxide resins are also commercially available.
  • Particles of encapsulated epoxy resin (microcapsules) according to the present disclosure comprise a shell surrounding a core of curable epoxy resin. Any suitable shell material may be used. The shell should be capable of preventing chemical reaction of the curable epoxy resin with species external to the shell, until activated.
  • Suitable shell materials may include organic polymers, such as, without limitation, polyurea, polyurethane, polymethylene urea, cured epoxy resin, and combinations thereof.
  • Particles of encapsulated epoxy resin may have an average diameter of 0.1-1000 micrometers, 1-1000 micrometers, 5-500 micrometers, or in some embodiments 30-300 micrometers.
  • Particles of encapsulated epoxy resin according to the present disclosure typically comprise an emulsifier as an artifact of their manufacture, typically present as a layer borne on the outer surface of the shell. Alternately, emulsifier may be removed after particle manufacture.
  • the emulsifier is oil-in-water Pickering emulsifier particles.
  • the emulsifier is an organic polymeric surfactant, typically a non-particulate organic polymeric surfactant.
  • the emulsifier is a combination of oil-in-water Pickering emulsifier particles, organic polymeric surfactant, or non-particulate organic polymeric surfactant.
  • the particles of encapsulated epoxy resin comprise not more than 50 wt% (based on the weight of oil-in-water Pickering emulsifier particles) of an organic polymeric surfactant or non-particulate organic polymeric surfactant; in some not more than 10 wt%; in some not more than 5 wt%; in some not more than 1 wt%, and in some not more than 0.1 wt%.
  • the emulsifier is oil-in water Pickering emulsifier particles
  • the resulting particles of encapsulated epoxy resin may be resistant to aggregation.
  • any suitable oil-in-water Pickering emulsifier particles may be used.
  • Pickering emulsifiers are particulate emulsifiers having a mixed hydrophilic/hydrophobic character.
  • Pickering emulsifiers suitable for oil-in-water emulsions are typically balanced in hydrophilic/hydrophobic character or somewhat more hydrophilic in character. In some instances, the desired balance of hydrophilic/hydrophobic properties can be characterized in terms of contact angle of the particle surface with water.
  • Contact angle may be measured by any suitable method, such as the method described in Paunov,“Novel Method for Determining the Three-Phase Contact Angle of Colloid Particles Adsorbed at Air-Water and Oil-Water Interfaces”, Langmuir 2003, 19, 7970-7976; the contents of which is incorporated by reference.
  • the outer surface of the oil-in-water Pickering emulsifier particles exhibits a contact angle with water of 50-95°; in some
  • Suitable oil-in-water Pickering emulsifier particles may include particles comprising silica, fumed silica, calcium carbonate, barium sulfate, clay, carbon black, iron oxide, carbon nanotubes, latex, block copolymer micelles, polystyrene, poly(methyl methacrylate), and combinations thereof.
  • any of the preceding materials may be surface-modified to alter hydrophilic/hydrophobic properties.
  • the oil-in-water Pickering emulsifier particles comprise fumed silica surface-modified with organic silanes or organic siloxanes.
  • Additional suitable Pickering emulsifiers may be listed in Chevalier et ah,“Emulsions stabilized with solid nanoparticles: Pickering emulsions”, Colloids and Surfaces A: Physicochem. Eng. Aspects 439 (2013) 23- 34; and Binks,“Particles as surfactants - similarities and differences”, Current Opinion in Colloid & Interface Science 7 (2002) 21-41; the contents of which is incorporated by reference.
  • the oil-in-water Pickering emulsifier particles may have an average diameter of 5-1000 nanometers, 5-500 nanometers,
  • particles of encapsulated epoxy resin may be manufactured as follows.
  • An aqueous suspension of oil-in water Pickering emulsifier particles 20 is mixed with an aqueous suspension of epoxy resin 10.
  • the aqueous suspension of epoxy resin 10 additionally includes a
  • step A the combined suspensions are emulsified by application of rapid mixing and moderate heat (e.g., 1000 rpm at 60°C) to form micelles 40
  • step B comprising epoxy resin core 15 and an outer layer of oil-in-water Pickering emulsifier particles 20.
  • a polyamine is added with continuing mixing. Polymerization reaction of the polyamine with the diisocyanate produces polyurea shell 30 surrounding epoxy resin core 15. Oil-in-water Pickering emulsifier particles 20 form an outer layer of the particle of encapsulated epoxy resin 50. Particles of encapsulated epoxy resin 50 may be collected by filtration and dried.
  • An organic polymeric surfactant or non particulate organic polymeric surfactant may be substituted for oil-in-water Pickering emulsifier particles 20 to form particles of encapsulated epoxy resin with a surface layer of organic polymeric surfactant or non-particulate organic polymeric surfactant instead of oil-in-water Pickering emulsifier particles.
  • the particles of encapsulated epoxy resin according to the present disclosure may be used in epoxy adhesive formulations. Since the curable epoxy is sequestered, the particles of encapsulated epoxy resin can be blended with epoxy curative to form one-part epoxy adhesives with long shelf life and high stability, yet which cure to form strong structural bonds. Such adhesive formulations may be solid or liquid at NTP. Cure may be initiated by activation of the particles of encapsulated epoxy resin so as to allow chemical reaction between the encapsulated epoxy resin and the curative.
  • Activation may be accomplished by any suitable method, which may include one or more of heat, mechanical disruption (e.g., by crushing between adherends, sonication, or the like) or other methods leading to shell rupture, shell wall thinning, shell wall softening, shell wall dissolution, shell wall permeablization, or the like.
  • the activation temperature may be, in various embodiments, not more than 200 °C, not more than 170 °C, not more than 110 °C, or not more than 80 °C.
  • Suitable epoxy curatives may be solid or liquid at NTP.
  • suitable curatives may be selected from polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof.
  • the curative may be partially cured or under-cured by reaction with a minor amount of an epoxy resin, which may be the same or different from the epoxy resin that forms the core of the particles of encapsulated epoxy resin. This approach may be used to render the curative a solid at NTP.
  • curable pressure sensitive adhesive tapes comprising: a) a pressure sensitive adhesive polymer; b) particles of encapsulated first epoxy resin (microcapsules) mixed into the pressure sensitive adhesive polymer; and c) an epoxy curative.
  • the epoxy curative is blended into the pressure sensitive adhesive.
  • the epoxy curative is the pressure sensitive adhesive polymer.
  • the epoxy curative is not encapsulated.
  • the curable pressure sensitive adhesive tape is a freestanding film.
  • the tape may be cured to form a structural bond between adherends.
  • Suitable epoxy curatives may be solid or liquid at NTP. Suitable epoxy curatives are NTP PSA’s, are modified to become NTP PSA’s, or are incorporated into NTP PSA’s. In various embodiments, suitable curatives may be selected from polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof.
  • the epoxy curative is the pressure sensitive adhesive polymer
  • a NTP solid curative with PSA character may be used.
  • the curative may be partially cured or under-cured by reaction with a minor amount of an epoxy resin, which may be the same or different from the epoxy resin that forms the core of the particles of encapsulated epoxy resin, to render it an NTP PSA material.
  • the PSA epoxy curative is an adduct of an epoxy curative and an epoxy resin in a ratio of at least 2: 1 second epoxy curative to second epoxy resin; in some embodiments at least 3: 1; in some embodiments at least 4: 1; in some embodiments at least 5: 1; in some embodiments at least 6: 1; in some embodiments at least 8:1; in some embodiments at least 10: 1.
  • NTP solid or NTP liquid epoxy curatives may be used.
  • any suitable PSA polymer may be used, which may include rubbers, poly(meth)acrylates, silicones, block copolymers, star block copolymers, or the like, any of which may be tackified or untackified.
  • curable pressure sensitive adhesive tapes according to the present disclosure may be manufactured by mixing particles of encapsulated epoxy resin according to the present disclosure into a NTP liquid epoxy curative and adding a minor amount of an epoxy resin, sufficient to render the epoxy curative a NTP solid PSA material upon cure.
  • the mixture may be coated out to an appropriate thickness and cured under conditions sufficient to cure the epoxy resin/epoxy curative mixture but not so rigorous as to activate the particles of encapsulated epoxy resin.
  • curable pressure sensitive adhesive tapes may be used to affix substrates or adherends by bringing the tape into contact with a first substrate; bringing the remaining exposed face of the tape into contact with a second substrate; and heating the curable pressure sensitive adhesive tape to a curing temperature, which is a temperature sufficient to activate the particles of encapsulated first epoxy resin and cure the first epoxy resin.
  • the curing temperature activation temperature
  • constructions obtained by the use of curable pressure sensitive adhesive tapes according to the present disclosure comprise a first substrate bound to a second substrate by a layer of cured epoxy resin.
  • the layer of cured epoxy resin is directly bound to the first substrate, the second substrate, or both.
  • Such constructions may be uniquely characterized by the presence of shells which are artifacts of the particles of encapsulated epoxy resin.
  • the shells may have an average diameter of 0.1-1000 micrometers, 1-1000 micrometers, 5-500 micrometers, or 30-300 micrometers.
  • the shells may comprise an organic polymer, such as polyurea, polyurethane, polymethylene urea, cured epoxy resin, or combinations thereof.
  • the shells may additionally comprise a layer of emulsifier borne on a surface of the shells in some embodiments, the shells may additionally comprise a layer of oil-in-water Pickering emulsifier particles borne on a surface of the shells, as described herein.
  • a curable pressure sensitive adhesive tape comprising:
  • the first epoxy curative is blended into the pressure sensitive adhesive or ii) the first epoxy curative is the pressure sensitive adhesive polymer.
  • T5 The curable pressure sensitive adhesive tape according to embodiment T4 wherein the first epoxy curative is an adduct of a second epoxy curative and a second epoxy resin in a ratio of at least 2: 1 second epoxy curative to second epoxy resin.
  • the curable pressure sensitive adhesive tape according to embodiment T5 wherein the second epoxy curative is selected from the group consisting of polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof.
  • T8 The curable pressure sensitive adhesive tape according to any of embodiments T1-T7 wherein the first epoxy curative is selected from the group consisting of polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof.
  • the first epoxy curative is selected from the group consisting of polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof.
  • T12 The curable pressure sensitive adhesive tape according to any of embodiments T10-T11 wherein the particles of encapsulated first epoxy resin additionally comprise a layer of inorganic particles borne on an outer surface of the shell.
  • T14 The curable pressure sensitive adhesive tape according to any of embodiments T1-T13 wherein the particles of encapsulated first epoxy resin have an average diameter of 0.1-1000 micrometers.
  • a method of affixing substrates comprising:
  • T16 The method according to embodiment T15, wherein the curing temperature is not more than 170 °C.
  • T17 The method according to embodiment T15, wherein the curing temperature is not more than 80 °C.
  • T18 A construction comprising a first substrate bound to a second substrate by a layer of cured epoxy resin, wherein the layer of cured epoxy resin comprises shells comprising an organic polymer.
  • T20 The construction according to any of embodiments T18-T19 wherein the shells comprise a layer of oil-in-water Pickering emulsifier particles borne on a surface of the shells.
  • T22 The construction according to any of embodiments T18-T21 wherein the shells have an average diameter of 0.1-1000 micrometers.
  • the particles according to embodiment PI comprising not more than 50 wt%, based on the weight of oil-in-water Pickering emulsifier particles, of an organic polymeric surfactant.
  • the particles according to embodiment PI comprising not more than 10 wt%, based on the weight of oil-in-water Pickering emulsifier particles, of an organic polymeric surfactant.
  • P5 The particles according to any of embodiments P1-P4 wherein the shell comprises an organic polymer selected from the group consisting of polyurea, polyurethane, polymethylene urea, cured epoxy resin, and combinations thereof.
  • the particles according to any of embodiments P1-P6 wherein the oil-in-water Pickering emulsifier particles comprise materials selected from the group consisting of silica, fumed silica, calcium carbonate, barium sulfate, clay, carbon black, iron oxide, carbon nanotubes, latex, block copolymer micelles, polystyrene, poly(methyl methacrylate), any of the preceding materials which additionally are surface-modified, and combinations thereof.
  • the particles according to any of embodiments P1-P6 wherein the oil-in-water Pickering emulsifier particles comprise fumed silica surface-modified with organic silanes or organic siloxanes.
  • the particles according to any of embodiments P1-P7 wherein the oil-in-water Pickering emulsifier particles have an outer surface, wherein the outer surface exhibits a contact angle with water of 50-95°.
  • P10 The particles according to any of embodiments P1-P7 wherein the oil-in-water Pickering emulsifier particles have an outer surface, wherein the outer surface exhibits a contact angle with water of 60-90°.
  • PI 1 The particles according to any of embodiments P1-P10 wherein the oil-in-water Pickering emulsifier particles have an average diameter of 5-1000 nanometers.
  • a composition comprising:
  • composition according to embodiment P14 wherein the first epoxy curative is an adduct of a second epoxy curative and a second epoxy resin in a ratio of at least 2: 1 second epoxy curative to second epoxy resin.
  • composition according to embodiment PI 5 wherein the second epoxy curative is selected from the group consisting of polyamides, polyamines,
  • polymercaptans anhydrides, imidazoles, and combinations thereof.
  • composition according to embodiment PI 5 wherein the second epoxy curative is a polyamide or polyamine.
  • PI 8 The composition according to any of embodiments P14-P17 wherein the first epoxy curative is selected from the group consisting of polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof.
  • P19 The composition according to any of embodiments P14-P17 wherein the first epoxy curative is a polyamide or polyamine.
  • the adhesive is a liquid at normal temperature and pressure (NTP).
  • the adhesive according to embodiment P20 which is a one-part structural adhesive.
  • a method of making particles of encapsulated first epoxy resin according to any of embodiments P1-P13 comprising:
  • MP2 The method according to embodiment MP1 wherein the first co-monomer is a diisocyanate or polyisocyanate.
  • MP3 The method according to embodiment MP1 or MP2 wherein the second co-monomer is a diamine, polyamine, diol, or polyol.
  • MP4 The method according to embodiment MP1 or MP2 wherein the second co-monomer is a diamine or polyamine.
  • the adhesive film was used to bond two 1” (2.54 cm) wide aluminum coupons with 0.5” (1.27 cm) overlap. Coupons were cleaned with acetone and allowed to dry before application of adhesive. The adhesive was cured at the indicated temperature for 1 hour. Some samples were clamped during cure, whereas other samples (“unclamped”) were not clamped and were hung vertically during cure. A dynamic overlap shear test was performed at ambient temperature using an Instron Tensile Tester (Instron, model 5581 equipped with a 10,000 N load cell).
  • Test specimens were loaded into the grips and the crosshead was operated at 10 mm per minute, loading the specimen to failure. Stress at break was recorded.
  • adhesive film samples were laminated with a VHB tape having a polyethylene backing, resulting in a tape with an overall adhesive thickness of ⁇ 1.0 mm.
  • the tape was adhered on the indicated substrates, with the adhesive film to be tested facing the substrate, using a #4.5 roller for 4 passes. Substrates were cleaned with acetone and allowed to dry before application of adhesive. Tapes were then peeled from substrates and 90° peel adhesion was measured using an Instron Tensile Tester (Instron, model 5581 equipped with a 500 N load cell) operated at 12” (30.5 cm) per minute.
  • the encapsulation was carried out in a jacketed 1L glass reactor fitted with a baffle.
  • the reactor temperature was controlled through a water bath.
  • a Ruston turban was used as the mixer and was placed 0.5” above the bottom of the reactor.
  • 4 g Aerosil R816 (for Example 1) or 4 g PVA (for Comparative Example A) was added into 400 mL water with a mixing rate at 1000 rpm at 60°C.
  • 30 g Lupranate 224 was mixed with 170 g Epon 815C in a beaker and the mixture was then added into the aqueous solution.
  • the emulsification was allowed for 10 min before 14.7 g diethylenetriamine (DETA) was added to the mixture.
  • DETA diethylenetriamine
  • Example 1 The size and size distribution of particles of encapsulated epoxy resin according to Example 1 and Comparative Example A were measured using Malvern Mastersizer (Malvern Panalytical Ltd., UK). Comparative Example A demonstrated an average particle size of 81 um with a broad distribution, while the average particle size of Example 1 was 114 um with a distribution several times narrower.
  • FIGS. 2(a)-(d) are SEM micrographs of particles of encapsulated epoxy resin according to Comparative Example A (FIGS. 2(a) and(b)) and Example 1 (FIGS. 2(c) and(d)).
  • the particles of Example 1 are more round and smooth. This suggests that the Pickering emulsifier used in Example 1 resulted in a more
  • Elemental analysis of the surface of particles of encapsulated epoxy resin according to Comparative Example A and Example 1 was studied using EDX.
  • the major elements on the surface of particles of Comparative Example A were carbon and oxygen, assignable to PVA.
  • the major elements on the surface of particles of Example 1 were carbon, oxygen, and silicon, demonstrating a surface layer of the surface- modified silica particles (Aerosil R816).
  • Elemental mapping of carbon, oxygen, and silicon on the surface of particles of Example 1 demonstrated 100% coverage of the surface with surface-modified silica particles.
  • Examples 2 & 3 Two liquid adhesive formulations (Examples 2 & 3) were made by manually mixing the particles of encapsulated epoxy resin of Example 1 (i.e., those made using Aerosil R816 as a Pickering emulsifier) with Anquamine 401 and Epikure 3115, respectively.
  • Anquamine 401 was dried at 60°C for 2 hours before mixing with particles of encapsulated epoxy resin from Example 1 at a weight ratio of 2:3.
  • Epikure 3115 was mixed with particles of encapsulated epoxy resin from Example 1 at a weight ratio of 1 : 1.
  • Samples of each of the two formulations were aged at two sets of conditions: at room temperature for 3 days, and at 70°C for 7 days. In all four cases, samples remained stable under the aging conditions. After aging, samples were taken and curing behavior was analyzed using DSC using TA Instruments Q100 with heating rate of 20°C/min to 310°.
  • the room temperature aged Example 2 and Example 3 showed onset temperatures at 151°C and 191°C, indicating the dependence of the onset temperature on the type of curative.
  • the 70°C/7days aged Example 2 formulation showed a lower onset temperature (135°C vs. 151°C) with a slightly reduced exotherm (266 J/g vs. 294 J/g) in comparison to the room temperature aged sample. Similar behavior was observed for the Example 3 formulation with lowered onset temperature and reduced exotherm.
  • Epikure 3115 was manually mixed with dry particles of encapsulated epoxy resin of Example 1 (i.e., those made using Aerosil R816 as a Pickering emulsifier) in a 10:9 weight ratio and the mixture was heated in oven at 40°C for 30 min. 1 part by weight (relative to Epickure 3115) of Epon 815C was then added to the mixture and manually mixed to an even distribution. The mixture was coated on a silicone release paper using a handheld knife coater to form a 0.5 mm thick adhesive film. The film was cured at 60°C for 1 hour, resulting in structural bonding tapes (transfer tapes) of Example 4.
  • the unclamped sample was hung vertically from a rack in the curing oven during the cure, yet did not separate or show delamination during or after cure due to the pressure sensitive adhesive character of the adhesive prior to cure. However, the corresponding clamped sample demonstrated greater shear strength than the unclamped sample. Visual examination of cured samples revealed that the clamped samples showed minor adhesive oozing from the sides due to the clamping force and adhesive flow at elevated temperature. It is estimated that there was 0.2 mm thickness of adhesive between the two coupons after curing which was responsible for the observed shear strength.
  • Curing temperature was evaluated in order to understand its influence on shear strength. 130 °C cure resulted in a low shear strength. High shear strength was obtained with cure at 160°C and 190°C. Without wishing to be bound by theory, Applicants believe the higher shear strength obtained at 160 °C versus 190 °C was due to greater flexibility in the 160 °C cured material, reflected by the higher value of elongation at break.
  • Various modifications and alterations of this disclosure will become apparent to those skilled in the art without departing from the scope and principles of this disclosure, and it should be understood that this disclosure is not to be unduly limited to the illustrative embodiments set forth hereinabove.

Abstract

Curable pressure sensitive adhesive tapes comprise: a) a pressure sensitive adhesive polymer; b) particles of encapsulated first epoxy resin (microcapsules) mixed into the pressure sensitive adhesive polymer; and c) a first epoxy curative. In some embodiments, the first epoxy curative is blended into the pressure sensitive adhesive. In other embodiments, the first epoxy curative is the pressure sensitive adhesive polymer. In some embodiments, the first epoxy curative may be an adduct of a second epoxy curative and a second epoxy resin in a ratio of at least 2:1 second epoxy curative to second epoxy resin. The particles of encapsulated first epoxy resin comprise a core of first epoxy resin within a shell comprising an organic polymer, and optionally a layer of oil-in-water Pickering emulsifier particles borne on a surface of the shells. Typically, the tape may be cured to form a structural bond between adherends.

Description

STRUCTURAL BONDING TAPE WITH EPOXIDE MICROCAPSULES
Field of the Disclosure
This disclosure relates to structural bonding tapes including particles of encapsulated epoxy resin blended with epoxy curative and methods and products of their use.
Background of the Disclosure
Pressure sensitive adhesives (PSA’s) are widely used in both industrial, commercial and residential applications due to their many advantages including easy application, instant handling strength, neat and precise bondline, and no need for mixing and dispensing. However, the adhesion of PSA is relatively low with the best PSA’s having a shear strength less than 3.45 MPa (500 psi), which limits their use in applications requiring structural adhesive strength. Traditional structural bonding tapes (SBT’s) offer high adhesion, but typically lack adhesion prior to thermal activation. In addition, SBT products may have limited stability and may require cold storage and shipping with dry-ice.
The following references may be relevant to the general field of technology of the present disclosure: CN 105833811; EP 1373426; EP 1530617; EP 2700683;
JP 2006/028254; US 2014/0272287; US 2015/0231588; US 4,536,524; US 5,601,761; US 6,506,494; US 7,927,514; US 8,084,519; and WO 201 1/126702.
Summary of the Disclosure
Briefly, the present disclosure provides curable pressure sensitive adhesive tapes comprising: a) a pressure sensitive adhesive polymer; b) particles of encapsulated first epoxy resin (microcapsules) mixed into the pressure sensitive adhesive polymer; and c) a first epoxy curative. In some embodiments, the first epoxy curative is blended into the pressure sensitive adhesive. In other embodiments, the first epoxy curative is the pressure sensitive adhesive polymer. Typically the first epoxy curative is not encapsulated. In various embodiments, the first epoxy curative is selected from polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof. Alternately, the first epoxy curative may be an adduct of a second epoxy curative and a second epoxy resin in a ratio of at least 2: 1 second epoxy curative to second epoxy resin. In various embodiments, the second epoxy curative is selected from polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and
combinations thereof. The particles of encapsulated first epoxy resin comprise a core of first epoxy resin within a shell comprising an organic polymer. In various embodiments, the shell comprises a polymer selected from the group consisting of polyurea, polyurethane, polymethylene urea, cured epoxy resin, and combinations thereof. The particles of encapsulated first epoxy resin may additionally comprise a layer of oil-in-water Pickering emulsifier particles borne on a surface of the shells. Typically, the tape may be cured to form a structural bond between adherends.
Additional embodiments of the curable pressure sensitive adhesive tapes of the present disclosure are described below under“Selected Embodiments.”
In another aspect, the present disclosure provides methods of affixing substrates, comprising: a) bringing a curable pressure sensitive adhesive tape according to any of the present disclosure into contact with a first substrate; b) bringing the curable pressure sensitive adhesive tape into contact with a second substrate; and c) heating the curable pressure sensitive adhesive tape to a curing temperature, which is a temperature sufficient to activate the particles of encapsulated first epoxy resin and cure the first epoxy resin. In various embodiments, the curing temperature may be not more than 200 °C, not more than 170 °C, not more than 110 °C, or not more than 80 °C. Additional embodiments of the method of affixing substrates of the present disclosure are described below under“Selected Embodiments.”
In another aspect, the present disclosure provides constructions comprising a first substrate bound to a second substrate by a layer of cured epoxy resin, wherein the layer of cured epoxy resin comprises shells comprising an organic polymer. In some embodiments, the shells comprise a polymer selected from the group consisting of polyurea, polyurethane, polymethylene urea, cured epoxy resin, and combinations thereof, and may additionally comprise a layer of oil-in-water Pickering emulsifier particles borne on a surface of the shells. Additional embodiments of the constructions of the present disclosure are described below under“Selected Embodiments.”
The preceding summary of the present disclosure is not intended to describe each embodiment of the present invention. The details of one or more embodiments of the invention are also set forth in the description below. Other features, objects, and advantages of the invention will be apparent from the description and from the claims.
In this application:
“activated” or“activation”, with regard to particles of encapsulated epoxy resin, means altered (e.g., by heat or mechanical disruption) so as to allow chemical reaction between the epoxy resin and species external to the particles, and may include without limitation shell rupture, shell wall thinning, shell wall softening, shell wall dissolution, or shell wall permeablization;
“directly bound” refers to two materials that are in direct contact with each other and bound together;
“free-standing film” means a film that is solid at normal temperature and pressure and has mechanical integrity independent of contact with any supporting material (which excludes, inter alia , liquids, surface coatings dried or cured in situ such as paints or primers, and surface coatings without independent mechanical integrity);
“(meth)acrylate” includes, separately and collectively, methacrylate and acrylate;
“normal temperature and pressure” or“NTP” means a temperature of 20 °C (293.15 K, 68 °F) and an absolute pressure of 1 atm (14.696 psi, 101.325 kPa);
“oil-in-water Pickering emulsifier particles” means particles suitable as
Pickering emulsifiers in an oil-in-water emulsion, which may have surfaces somewhat more hydrophilic than hydrophobic in character or evenly hydrophilic/hydrophobic in character (which may be reflected in exhibiting a contact angle of the particle surface with water of 50-95° or 60-90°), and which may have an average diameter of 5-1000 nanometers;
“pressure sensitive adhesive (PSA)” means materials having the following properties: a) aggressive and permanent tack, b) the ability to adhere with no more than finger pressure, c) the ability to adhere without activation by any energy source, d) sufficient ability to hold onto the intended adherend, and preferably e) sufficient cohesive strength to be removed cleanly from the adherend; which materials typically meet the Dahlquist criterion of having a storage modulus at 1 Hz and room temperature of less than 0.3MPa; and “structural adhesive” means an adhesive that binds by irreversible cure, typically with a strength when bound to its intended substrates, measured as stress at break (peak stress) using the overlap shear test described in the Examples herein, of at least 4.14 MPa (600 psi), more typically at least 5.52 MPa (800 psi), in some embodiments at least 6.89 MPa (1000 psi), and in some embodiments at least 8.27 MPa (1200 psi).
All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified.
As used in this specification and the appended claims, past tense verbs such as “coated” and are intended to represent structure, and not to limit the process used to obtain the recited structure, unless otherwise specified.
As used in this specification and the appended claims, the singular forms“a”, “an”, and“the” encompass embodiments having plural referents, unless the content clearly dictates otherwise.
As used in this specification and the appended claims, the term“or” is generally employed in its sense including“and/or” unless the content clearly dictates otherwise.
As used herein,“have”,“having”,“include”,“including”,“comprise”, “comprising” or the like are used in their open ended sense, and generally mean “including, but not limited to.” It will be understood that the terms“consisting of’ and “consisting essentially of’ are subsumed in the term“comprising,” and the like.
Brief Description of the Drawing
FIG. 1 schematically depicts a process of forming particles of encapsulated epoxy resin using a Pickering emulsifier.
FIGS. 2(a)-(d) are scanning electron micrographs of particles of encapsulated epoxy resin as described in the Examples herein.
Detailed Description
The present disclosure provides curable pressure sensitive adhesive tapes comprising: a) a pressure sensitive adhesive polymer; b) particles of encapsulated first epoxy resin (microcapsules) mixed into the pressure sensitive adhesive polymer; and c) a first epoxy curative. In some embodiments, the first epoxy curative is blended into the pressure sensitive adhesive. In other embodiments, the first epoxy curative is the pressure sensitive adhesive polymer. Typically the first epoxy curative is not encapsulated. Typically, the tape may be cured to form a structural bond between adherends.
The present disclosure also provides particles of encapsulated first epoxy resin (microcapsules) comprising a) a core of first epoxy resin, within b) a shell comprising an organic polymer, and c) a layer of oil-in-water Pickering emulsifier particles borne on an outer surface of the shell. These particles may be used in liquid adhesive compositions, in the tapes described above, or in other applications. Since the curable epoxy is sequestered, the particles of encapsulated epoxy resin can be blended with epoxy curative to form one-part epoxy adhesives with long shelf life and high stability, yet which cure to form strong structural bonds.
Figure imgf000007_0001
Particles of encapsulated epoxy resin (microcapsules) according to the present disclosure comprise a core of curable epoxy resin enclosed in a shell. The outer surface of the shell may include an emulsifier.
Any suitable curable epoxy resin may be used, that is, any suitable organic compound having one or more oxirane rings polymerizable by a ring opening reaction. Suitable curable epoxy resins may include monomeric epoxy compounds and polymeric epoxy compounds and can be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyclic, or can comprise combinations thereof. Useful materials typically have at least two polymerizable epoxy groups per molecule (that is, polyepoxides) and, more preferably, from two to four polymerizable epoxy groups per molecule. In some embodiments the curable epoxy resin is a liquid at NTP. In some embodiments the curable epoxy resin is a solid at NTP.
Suitable curable epoxy resins may include the polyglycidyl ethers of polyhydric phenols (for example, bisphenol A derivative resins, epoxy cresol-novolac resins, bisphenol F derivative resins, epoxy phenol -novolac resins), glycidyl esters of aromatic carboxylic acids, glycidyl amines of aromatic amines, and the like, and mixtures thereof. Representative examples of aliphatic polyepoxides that can be utilized include 3 ',4'-epoxycyclohexylmethyl-3, 4-epoxy cy cl ohexanecarboxylate, 2-(3',4'- epoxy cy cl ohexyl)-5,l "-spiro-3 ",4"-epoxycyclohexane-l,3-dioxane, bis(3,4- epoxycyclohexylmethyl)adipate, the diglycidyl ester of linoleic dimer acid,
1 ,4-bis(2,3 -epoxypropoxy)butane, 4-( 1 ,2-epoxy ethyl)- 1 ,2-epoxy cyclohexane, 2,2- bis(3, 4-epoxy cyclohexyl)propane, polyglycidyl ethers of aliphatic polyols such as glycerol or hydrogenated 4,4'-dihydroxydiphenyl-dimethylmethane, and the like, and mixtures thereof. Representative examples of aromatic polyepoxides that can be utilized include glycidyl esters of aromatic carboxylic acids (for example, phthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, trimellitic acid triglycidyl ester, pyromellitic acid tetraglycidyl ester, and the like, and mixtures thereof); N- glycidylaminobenzenes (for example, N,N-diglycidylbenzeneamine, bis(N,N- diglycidyl-4-aminophenyl)methane, l,3-bis(N,N-diglycidylamino)benzene, N,N- diglycidyl-4-glycidyloxybenzeneamine, and the like, and mixtures thereof); the polyglycidyl derivatives of polyhydric phenols (for example, the polyglycidyl ethers of polyhydric phenols such as 2,2-bis-[4-hydroxyphenyl]propane, tetrakis(4- hydroxyphenyl)ethane, pyrocatechol, resorcinol, hydroquinone, 4,4'-dihydroxydiphenyl methane, 4, 4'-dihydroxy diphenyl dimethyl methane, 4,4'-dihydroxy-3,3'- dimethyldiphenyl methane, 4,4'-dihydroxydiphenyl methyl methane, 4,4'- dihydroxy diphenyl cyclohexane, 4,4'-dihydroxy-3,3'-dimethyldiphenyl propane, 4,4'- dihydroxydiphenyl sulfone, and tris-(4-hydroxyphenyl)methane); polyglycidyl ethers of novolacs (reaction products of monohydric or polyhydric phenols with aldehydes in the presence of acid catalysts), and the derivatives described in U.S. Patent Nos. 3,018,262 (Schoeder) and 3,298,998 (Coover et ah), the descriptions of which are incorporated herein by reference, as well as the derivatives described in the Handbook of Epoxy
Figure imgf000008_0001
Inc., New York (1988); and the like; and mixtures thereof. Suitable epoxy resins can be prepared by, for example, the reaction of epichlorohydrin with a polyol, as described, for example, in U.S. Patent No. 4,522,958 (Das et ah), the description of which is incorporated herein by reference, as well as by other methods described by Lee and Neville and by May, supra. Many epoxide resins are also commercially available. Particles of encapsulated epoxy resin (microcapsules) according to the present disclosure comprise a shell surrounding a core of curable epoxy resin. Any suitable shell material may be used. The shell should be capable of preventing chemical reaction of the curable epoxy resin with species external to the shell, until activated. Upon activation, the shell is altered such that the curable epoxy resin core may react with species external to the particle. Suitable shell materials may include organic polymers, such as, without limitation, polyurea, polyurethane, polymethylene urea, cured epoxy resin, and combinations thereof.
Particles of encapsulated epoxy resin may have an average diameter of 0.1-1000 micrometers, 1-1000 micrometers, 5-500 micrometers, or in some embodiments 30-300 micrometers.
Particles of encapsulated epoxy resin according to the present disclosure typically comprise an emulsifier as an artifact of their manufacture, typically present as a layer borne on the outer surface of the shell. Alternately, emulsifier may be removed after particle manufacture. In some embodiments, the emulsifier is oil-in-water Pickering emulsifier particles. In some embodiments, the emulsifier is an organic polymeric surfactant, typically a non-particulate organic polymeric surfactant. In some embodiments, the emulsifier is a combination of oil-in-water Pickering emulsifier particles, organic polymeric surfactant, or non-particulate organic polymeric surfactant. In some embodiments, the particles of encapsulated epoxy resin comprise not more than 50 wt% (based on the weight of oil-in-water Pickering emulsifier particles) of an organic polymeric surfactant or non-particulate organic polymeric surfactant; in some not more than 10 wt%; in some not more than 5 wt%; in some not more than 1 wt%, and in some not more than 0.1 wt%. In embodiments where the emulsifier is oil-in water Pickering emulsifier particles, the resulting particles of encapsulated epoxy resin may be resistant to aggregation.
Where a Pickering emulsifier is used, any suitable oil-in-water Pickering emulsifier particles may be used. Pickering emulsifiers are particulate emulsifiers having a mixed hydrophilic/hydrophobic character. Pickering emulsifiers suitable for oil-in-water emulsions are typically balanced in hydrophilic/hydrophobic character or somewhat more hydrophilic in character. In some instances, the desired balance of hydrophilic/hydrophobic properties can be characterized in terms of contact angle of the particle surface with water. Contact angle may be measured by any suitable method, such as the method described in Paunov,“Novel Method for Determining the Three-Phase Contact Angle of Colloid Particles Adsorbed at Air-Water and Oil-Water Interfaces”, Langmuir 2003, 19, 7970-7976; the contents of which is incorporated by reference. In some embodiments, the outer surface of the oil-in-water Pickering emulsifier particles exhibits a contact angle with water of 50-95°; in some
embodiments 60-90°; in some embodiments 70-90°; and in some embodiments 75-90°. Suitable oil-in-water Pickering emulsifier particles may include particles comprising silica, fumed silica, calcium carbonate, barium sulfate, clay, carbon black, iron oxide, carbon nanotubes, latex, block copolymer micelles, polystyrene, poly(methyl methacrylate), and combinations thereof. In addition, any of the preceding materials may be surface-modified to alter hydrophilic/hydrophobic properties. In one preferred embodiment, the oil-in-water Pickering emulsifier particles comprise fumed silica surface-modified with organic silanes or organic siloxanes. Additional suitable Pickering emulsifiers may be listed in Chevalier et ah,“Emulsions stabilized with solid nanoparticles: Pickering emulsions”, Colloids and Surfaces A: Physicochem. Eng. Aspects 439 (2013) 23- 34; and Binks,“Particles as surfactants - similarities and differences”, Current Opinion in Colloid & Interface Science 7 (2002) 21-41; the contents of which is incorporated by reference. The oil-in-water Pickering emulsifier particles may have an average diameter of 5-1000 nanometers, 5-500 nanometers,
5-200 nanometers, 5-100 nanometers, or in some embodiments 5-50 nanometers.
With reference to FIG. 1, particles of encapsulated epoxy resin according to the present disclosure may be manufactured as follows. An aqueous suspension of oil-in water Pickering emulsifier particles 20 is mixed with an aqueous suspension of epoxy resin 10. The aqueous suspension of epoxy resin 10 additionally includes a
diisocyanate. In step A, the combined suspensions are emulsified by application of rapid mixing and moderate heat (e.g., 1000 rpm at 60°C) to form micelles 40
comprising epoxy resin core 15 and an outer layer of oil-in-water Pickering emulsifier particles 20. In step B, a polyamine is added with continuing mixing. Polymerization reaction of the polyamine with the diisocyanate produces polyurea shell 30 surrounding epoxy resin core 15. Oil-in-water Pickering emulsifier particles 20 form an outer layer of the particle of encapsulated epoxy resin 50. Particles of encapsulated epoxy resin 50 may be collected by filtration and dried. An organic polymeric surfactant or non particulate organic polymeric surfactant may be substituted for oil-in-water Pickering emulsifier particles 20 to form particles of encapsulated epoxy resin with a surface layer of organic polymeric surfactant or non-particulate organic polymeric surfactant instead of oil-in-water Pickering emulsifier particles.
The particles of encapsulated epoxy resin according to the present disclosure may be used in epoxy adhesive formulations. Since the curable epoxy is sequestered, the particles of encapsulated epoxy resin can be blended with epoxy curative to form one-part epoxy adhesives with long shelf life and high stability, yet which cure to form strong structural bonds. Such adhesive formulations may be solid or liquid at NTP. Cure may be initiated by activation of the particles of encapsulated epoxy resin so as to allow chemical reaction between the encapsulated epoxy resin and the curative.
Activation may be accomplished by any suitable method, which may include one or more of heat, mechanical disruption (e.g., by crushing between adherends, sonication, or the like) or other methods leading to shell rupture, shell wall thinning, shell wall softening, shell wall dissolution, shell wall permeablization, or the like. When heat is used to activate the particles of encapsulated epoxy resin, the activation temperature may be, in various embodiments, not more than 200 °C, not more than 170 °C, not more than 110 °C, or not more than 80 °C.
Any suitable epoxy curative may be used with the particles of encapsulated epoxy resin according to the present disclosure. Suitable epoxy curatives may be solid or liquid at NTP. In some embodiments, suitable curatives may be selected from polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof. In some embodiments, the curative may be partially cured or under-cured by reaction with a minor amount of an epoxy resin, which may be the same or different from the epoxy resin that forms the core of the particles of encapsulated epoxy resin. This approach may be used to render the curative a solid at NTP.
Figure imgf000011_0001
The present disclosure provides curable pressure sensitive adhesive tapes comprising: a) a pressure sensitive adhesive polymer; b) particles of encapsulated first epoxy resin (microcapsules) mixed into the pressure sensitive adhesive polymer; and c) an epoxy curative. In some embodiments, the epoxy curative is blended into the pressure sensitive adhesive. In other embodiments, the epoxy curative is the pressure sensitive adhesive polymer. Typically, the epoxy curative is not encapsulated.
Typically, the curable pressure sensitive adhesive tape is a freestanding film.
Typically, the tape may be cured to form a structural bond between adherends.
Any suitable epoxy curative may be used in the tapes according to the present disclosure. Suitable epoxy curatives may be solid or liquid at NTP. Suitable epoxy curatives are NTP PSA’s, are modified to become NTP PSA’s, or are incorporated into NTP PSA’s. In various embodiments, suitable curatives may be selected from polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof.
In embodiments where the epoxy curative is the pressure sensitive adhesive polymer, a NTP solid curative with PSA character may be used. In some such embodiments, the curative may be partially cured or under-cured by reaction with a minor amount of an epoxy resin, which may be the same or different from the epoxy resin that forms the core of the particles of encapsulated epoxy resin, to render it an NTP PSA material. In some such embodiments the PSA epoxy curative is an adduct of an epoxy curative and an epoxy resin in a ratio of at least 2: 1 second epoxy curative to second epoxy resin; in some embodiments at least 3: 1; in some embodiments at least 4: 1; in some embodiments at least 5: 1; in some embodiments at least 6: 1; in some embodiments at least 8:1; in some embodiments at least 10: 1.
In embodiments where the epoxy curative is blended into a pressure sensitive adhesive polymer, NTP solid or NTP liquid epoxy curatives may be used. In such embodiments, any suitable PSA polymer may be used, which may include rubbers, poly(meth)acrylates, silicones, block copolymers, star block copolymers, or the like, any of which may be tackified or untackified.
In some embodiments, curable pressure sensitive adhesive tapes according to the present disclosure may be manufactured by mixing particles of encapsulated epoxy resin according to the present disclosure into a NTP liquid epoxy curative and adding a minor amount of an epoxy resin, sufficient to render the epoxy curative a NTP solid PSA material upon cure. The mixture may be coated out to an appropriate thickness and cured under conditions sufficient to cure the epoxy resin/epoxy curative mixture but not so rigorous as to activate the particles of encapsulated epoxy resin.
In some embodiments, curable pressure sensitive adhesive tapes according to the present disclosure may be used to affix substrates or adherends by bringing the tape into contact with a first substrate; bringing the remaining exposed face of the tape into contact with a second substrate; and heating the curable pressure sensitive adhesive tape to a curing temperature, which is a temperature sufficient to activate the particles of encapsulated first epoxy resin and cure the first epoxy resin. The curing temperature (activation temperature) may be, in various embodiments, not more than 200 °C, not more than 170 °C, not more than 110 °C, or not more than 80 °C.
In some embodiments, constructions obtained by the use of curable pressure sensitive adhesive tapes according to the present disclosure comprise a first substrate bound to a second substrate by a layer of cured epoxy resin. In some such cases, the layer of cured epoxy resin is directly bound to the first substrate, the second substrate, or both. Such constructions may be uniquely characterized by the presence of shells which are artifacts of the particles of encapsulated epoxy resin. The shells may have an average diameter of 0.1-1000 micrometers, 1-1000 micrometers, 5-500 micrometers, or 30-300 micrometers. The shells may comprise an organic polymer, such as polyurea, polyurethane, polymethylene urea, cured epoxy resin, or combinations thereof. The shells may additionally comprise a layer of emulsifier borne on a surface of the shells in some embodiments, the shells may additionally comprise a layer of oil-in-water Pickering emulsifier particles borne on a surface of the shells, as described herein.
Additional embodiments are recited in the Selected Embodiments and
Examples below.
Selected Embodiments
The following embodiments, designated by letter and number, are intended to further illustrate the present disclosure but should not be construed to unduly limit this disclosure.
T1. A curable pressure sensitive adhesive tape comprising:
a) a pressure sensitive adhesive polymer; b) particles of encapsulated first epoxy resin mixed into the pressure sensitive adhesive polymer; and
c) a first epoxy curative;
wherein i) the first epoxy curative is blended into the pressure sensitive adhesive or ii) the first epoxy curative is the pressure sensitive adhesive polymer.
T2. The curable pressure sensitive adhesive tape according to embodiment T1 wherein the first epoxy curative is not encapsulated.
T3. The curable pressure sensitive adhesive tape according to embodiment T1 or T2 wherein the first epoxy curative is blended into the pressure sensitive adhesive.
T4. The curable pressure sensitive adhesive tape according to embodiment T1 or T2 wherein the first epoxy curative is the pressure sensitive adhesive.
T5. The curable pressure sensitive adhesive tape according to embodiment T4 wherein the first epoxy curative is an adduct of a second epoxy curative and a second epoxy resin in a ratio of at least 2: 1 second epoxy curative to second epoxy resin.
T6. The curable pressure sensitive adhesive tape according to embodiment T5 wherein the second epoxy curative is selected from the group consisting of polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof.
T7. The curable pressure sensitive adhesive tape according to embodiment T5 wherein the second epoxy curative is a polyamide or a polyamine.
T8. The curable pressure sensitive adhesive tape according to any of embodiments T1-T7 wherein the first epoxy curative is selected from the group consisting of polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof.
T9. The curable pressure sensitive adhesive tape according to any of embodiments T1-T7 wherein the first epoxy curative is a polyamide or a polyamine. T10. The curable pressure sensitive adhesive tape according to any of embodiments T1-T9 wherein the particles of encapsulated first epoxy resin comprise a core of first epoxy resin within a shell comprising an organic polymer.
Ti l. The curable pressure sensitive adhesive tape according to embodiment T10 wherein the shell comprises a polymer selected from the group consisting of polyurea, polyurethane, polymethylene urea, cured epoxy resin, and combinations thereof.
T12. The curable pressure sensitive adhesive tape according to any of embodiments T10-T11 wherein the particles of encapsulated first epoxy resin additionally comprise a layer of inorganic particles borne on an outer surface of the shell.
T13. The curable pressure sensitive adhesive tape according to embodiment T12 wherein the inorganic particles comprise fumed silica.
T14. The curable pressure sensitive adhesive tape according to any of embodiments T1-T13 wherein the particles of encapsulated first epoxy resin have an average diameter of 0.1-1000 micrometers.
T15. A method of affixing substrates comprising:
a) bringing a curable pressure sensitive adhesive tape according to any of embodiments T1-T14 into contact with a first substrate;
b) bringing the curable pressure sensitive adhesive tape into contact with a second substrate; and
c) heating the curable pressure sensitive adhesive tape to a curing temperature, which is a temperature sufficient to activate the particles of encapsulated first epoxy resin and cure the first epoxy resin.
T16. The method according to embodiment T15, wherein the curing temperature is not more than 170 °C. T17. The method according to embodiment T15, wherein the curing temperature is not more than 80 °C.
T18. A construction comprising a first substrate bound to a second substrate by a layer of cured epoxy resin, wherein the layer of cured epoxy resin comprises shells comprising an organic polymer.
T19. The construction according to embodiment T18 wherein the shells comprise a polymer selected from the group consisting of polyurea, polyurethane, polymethylene urea, cured epoxy resin, and combinations thereof.
T20. The construction according to any of embodiments T18-T19 wherein the shells comprise a layer of oil-in-water Pickering emulsifier particles borne on a surface of the shells.
T21. The construction according to embodiment T20 wherein the oil-in-water Pickering emulsifier particles comprise fumed silica.
T22. The construction according to any of embodiments T18-T21 wherein the shells have an average diameter of 0.1-1000 micrometers.
T23. The curable pressure sensitive adhesive tape according to any of embodiments T1-T14 wherein the particles of encapsulated first epoxy resin are the particles of encapsulated first epoxy resin according to any of embodiments PI -PI 3.
PI . Particles of encapsulated first epoxy resin comprising
a) a core of first epoxy resin, within
b) a shell comprising an organic polymer, and
c) a layer of oil-in-water Pickering emulsifier particles borne on an outer surface of the shell. P2. The particles according to embodiment PI comprising not more than 50 wt%, based on the weight of oil-in-water Pickering emulsifier particles, of an organic polymeric surfactant.
P3. The particles according to embodiment PI comprising not more than 10 wt%, based on the weight of oil-in-water Pickering emulsifier particles, of an organic polymeric surfactant.
P4. The particles according to any of embodiments P1-P3 having an average diameter of 0.1-1000 micrometers.
P5. The particles according to any of embodiments P1-P4 wherein the shell comprises an organic polymer selected from the group consisting of polyurea, polyurethane, polymethylene urea, cured epoxy resin, and combinations thereof.
P6. The particles according to any of embodiments P1-P4 wherein the shell comprises a polyurea polymer.
P7. The particles according to any of embodiments P1-P6 wherein the oil-in-water Pickering emulsifier particles comprise materials selected from the group consisting of silica, fumed silica, calcium carbonate, barium sulfate, clay, carbon black, iron oxide, carbon nanotubes, latex, block copolymer micelles, polystyrene, poly(methyl methacrylate), any of the preceding materials which additionally are surface-modified, and combinations thereof.
P8. The particles according to any of embodiments P1-P6 wherein the oil-in-water Pickering emulsifier particles comprise fumed silica surface-modified with organic silanes or organic siloxanes.
P9. The particles according to any of embodiments P1-P7 wherein the oil-in-water Pickering emulsifier particles have an outer surface, wherein the outer surface exhibits a contact angle with water of 50-95°. P10. The particles according to any of embodiments P1-P7 wherein the oil-in-water Pickering emulsifier particles have an outer surface, wherein the outer surface exhibits a contact angle with water of 60-90°.
PI 1. The particles according to any of embodiments P1-P10 wherein the oil-in-water Pickering emulsifier particles have an average diameter of 5-1000 nanometers.
P12. The particles according to any of embodiments Pl-Pl 1 which activate upon heating to a activation temperature, wherein the activation temperature is not more than 170 °C.
P13. The particles according to embodiment PI 2, wherein the activation temperature is not more than 80 °C.
P14. A composition comprising:
A) the particles according to any of embodiments PI -PI 3, blended with
B) a first epoxy curative.
PI 5. The composition according to embodiment P14 wherein the first epoxy curative is an adduct of a second epoxy curative and a second epoxy resin in a ratio of at least 2: 1 second epoxy curative to second epoxy resin.
PI 6. The composition according to embodiment PI 5 wherein the second epoxy curative is selected from the group consisting of polyamides, polyamines,
polymercaptans, anhydrides, imidazoles, and combinations thereof.
PI 7. The composition according to embodiment PI 5 wherein the second epoxy curative is a polyamide or polyamine.
PI 8. The composition according to any of embodiments P14-P17 wherein the first epoxy curative is selected from the group consisting of polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof. P19. The composition according to any of embodiments P14-P17 wherein the first epoxy curative is a polyamide or polyamine.
P20. An adhesive comprising
I) particles of encapsulated first epoxy resin comprising
a) a core of first epoxy resin, within
b) a shell comprising an organic polymer, and
c) a layer of oil-in-water Pickering emulsifier particles borne on an outer surface of the shell;
blended with
II) a first epoxy curative;
wherein the adhesive is a liquid at normal temperature and pressure (NTP).
P21. The adhesive according to embodiment P20 which is a one-part structural adhesive.
MP1. A method of making particles of encapsulated first epoxy resin according to any of embodiments P1-P13 comprising:
A) blending in aqueous suspension
i) a curable epoxy resin,
ii) oil-in-water Pickering emulsifier particles, and
iii) a first co-monomer
to form a blend;
B) emulsifying the blend to form micelles comprising a core of curable epoxy resin and an outer layer of oil-in-water Pickering emulsifier particles;
C) adding a second co-monomer reactive with the first co-monomer to form a copolymer; and
D) copolymerizing the first and second co-monomers to form a copolymer shell enclosing the core of curable epoxy resin.
MP2. The method according to embodiment MP1 wherein the first co-monomer is a diisocyanate or polyisocyanate. MP3. The method according to embodiment MP1 or MP2 wherein the second co-monomer is a diamine, polyamine, diol, or polyol.
MP4. The method according to embodiment MP1 or MP2 wherein the second co-monomer is a diamine or polyamine.
Objects and advantages of this disclosure are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.
Examples
Unless otherwise noted, all reagents were obtained or are available from Aldrich Chemical Co., Milwaukee, WI, or may be synthesized by known methods.
MATERIALS
Figure imgf000020_0001
TEST METHODS
Overlay Shear Strength Test
For overlap sheer strength measurement, the adhesive film was used to bond two 1” (2.54 cm) wide aluminum coupons with 0.5” (1.27 cm) overlap. Coupons were cleaned with acetone and allowed to dry before application of adhesive. The adhesive was cured at the indicated temperature for 1 hour. Some samples were clamped during cure, whereas other samples (“unclamped”) were not clamped and were hung vertically during cure. A dynamic overlap shear test was performed at ambient temperature using an Instron Tensile Tester (Instron, model 5581 equipped with a 10,000 N load cell).
Test specimens were loaded into the grips and the crosshead was operated at 10 mm per minute, loading the specimen to failure. Stress at break was recorded.
90° Peel Test
For the peel test, adhesive film samples were laminated with a VHB tape having a polyethylene backing, resulting in a tape with an overall adhesive thickness of ~1.0 mm. The tape was adhered on the indicated substrates, with the adhesive film to be tested facing the substrate, using a #4.5 roller for 4 passes. Substrates were cleaned with acetone and allowed to dry before application of adhesive. Tapes were then peeled from substrates and 90° peel adhesion was measured using an Instron Tensile Tester (Instron, model 5581 equipped with a 500 N load cell) operated at 12” (30.5 cm) per minute.
EXAMPLES
Preparation and Characterization of Particles of Encapsulated Epoxy Resin (Ex. 1, C.Ex. A)
The encapsulation was carried out in a jacketed 1L glass reactor fitted with a baffle. The reactor temperature was controlled through a water bath. A Ruston turban was used as the mixer and was placed 0.5” above the bottom of the reactor. In the reactor, 4 g Aerosil R816 (for Example 1) or 4 g PVA (for Comparative Example A) was added into 400 mL water with a mixing rate at 1000 rpm at 60°C. Separately, 30 g Lupranate 224 was mixed with 170 g Epon 815C in a beaker and the mixture was then added into the aqueous solution. The emulsification was allowed for 10 min before 14.7 g diethylenetriamine (DETA) was added to the mixture. After certain reaction time, the suspension was filtered and the particles of encapsulated epoxy resin were washed with water on the filter and dried in oven at 70°C for 2 hours.
After drying, particles of encapsulated epoxy resin according to Comparative Example A were found to clump to form aggregates that were a little rubbery and difficult to break down. In contrast, particles of encapsulated epoxy resin according to Example 1 could be easily separated into discrete particles and the resulting powder had good flowability.
The size and size distribution of particles of encapsulated epoxy resin according to Example 1 and Comparative Example A were measured using Malvern Mastersizer (Malvern Panalytical Ltd., UK). Comparative Example A demonstrated an average particle size of 81 um with a broad distribution, while the average particle size of Example 1 was 114 um with a distribution several times narrower.
The morphology of particles of encapsulated epoxy resin according to
Comparative Example A and Example 1 was studied using SEM using a Hitachi FlexSEM 1000. FIGS. 2(a)-(d) are SEM micrographs of particles of encapsulated epoxy resin according to Comparative Example A (FIGS. 2(a) and(b)) and Example 1 (FIGS. 2(c) and(d)). Compared to particles of encapsulated epoxy resin according to Comparative Example A, the particles of Example 1 are more round and smooth. This suggests that the Pickering emulsifier used in Example 1 resulted in a more
mechanically stable emulsion.
Elemental analysis of the surface of particles of encapsulated epoxy resin according to Comparative Example A and Example 1 was studied using EDX. The major elements on the surface of particles of Comparative Example A were carbon and oxygen, assignable to PVA. The major elements on the surface of particles of Example 1 were carbon, oxygen, and silicon, demonstrating a surface layer of the surface- modified silica particles (Aerosil R816). Elemental mapping of carbon, oxygen, and silicon on the surface of particles of Example 1 demonstrated 100% coverage of the surface with surface-modified silica particles. Preparation and Characterization of Liquid Adhesive Formulations (Exs 2 &3)
Two liquid adhesive formulations (Examples 2 & 3) were made by manually mixing the particles of encapsulated epoxy resin of Example 1 (i.e., those made using Aerosil R816 as a Pickering emulsifier) with Anquamine 401 and Epikure 3115, respectively. Anquamine 401 was dried at 60°C for 2 hours before mixing with particles of encapsulated epoxy resin from Example 1 at a weight ratio of 2:3. Epikure 3115 was mixed with particles of encapsulated epoxy resin from Example 1 at a weight ratio of 1 : 1.
Samples of each of the two formulations were aged at two sets of conditions: at room temperature for 3 days, and at 70°C for 7 days. In all four cases, samples remained stable under the aging conditions. After aging, samples were taken and curing behavior was analyzed using DSC using TA Instruments Q100 with heating rate of 20°C/min to 310°. The room temperature aged Example 2 and Example 3 showed onset temperatures at 151°C and 191°C, indicating the dependence of the onset temperature on the type of curative. The 70°C/7days aged Example 2 formulation showed a lower onset temperature (135°C vs. 151°C) with a slightly reduced exotherm (266 J/g vs. 294 J/g) in comparison to the room temperature aged sample. Similar behavior was observed for the Example 3 formulation with lowered onset temperature and reduced exotherm.
Preparation and Characteriation of Structural Bondins Tapes (Ex. 4)
Epikure 3115 was manually mixed with dry particles of encapsulated epoxy resin of Example 1 (i.e., those made using Aerosil R816 as a Pickering emulsifier) in a 10:9 weight ratio and the mixture was heated in oven at 40°C for 30 min. 1 part by weight (relative to Epickure 3115) of Epon 815C was then added to the mixture and manually mixed to an even distribution. The mixture was coated on a silicone release paper using a handheld knife coater to form a 0.5 mm thick adhesive film. The film was cured at 60°C for 1 hour, resulting in structural bonding tapes (transfer tapes) of Example 4.
90° peel testing was performed on the uncured structural bonding tape of Example 4 in accordance with the procedure described above, using stainless steel, glass, PVC, and LDPE substrates. The results, summarized in Table 1, demonstrate that the structural bonding tape of Example 4 has pressure sensitive adhesive character prior to cure.
Table 1
Figure imgf000024_0001
Overlap shear strength testing was performed on the structural bonding tape of Example 4 in accordance with the procedure described above. Results are summarized in Table 2.
Table 2
Figure imgf000024_0002
The unclamped sample was hung vertically from a rack in the curing oven during the cure, yet did not separate or show delamination during or after cure due to the pressure sensitive adhesive character of the adhesive prior to cure. However, the corresponding clamped sample demonstrated greater shear strength than the unclamped sample. Visual examination of cured samples revealed that the clamped samples showed minor adhesive oozing from the sides due to the clamping force and adhesive flow at elevated temperature. It is estimated that there was 0.2 mm thickness of adhesive between the two coupons after curing which was responsible for the observed shear strength.
Curing temperature was evaluated in order to understand its influence on shear strength. 130 °C cure resulted in a low shear strength. High shear strength was obtained with cure at 160°C and 190°C. Without wishing to be bound by theory, Applicants believe the higher shear strength obtained at 160 °C versus 190 °C was due to greater flexibility in the 160 °C cured material, reflected by the higher value of elongation at break. Various modifications and alterations of this disclosure will become apparent to those skilled in the art without departing from the scope and principles of this disclosure, and it should be understood that this disclosure is not to be unduly limited to the illustrative embodiments set forth hereinabove.

Claims

We claim:
1. A curable pressure sensitive adhesive tape comprising:
a) a pressure sensitive adhesive polymer;
b) particles of encapsulated first epoxy resin mixed into the pressure sensitive adhesive polymer; and
c) a first epoxy curative;
wherein i) the first epoxy curative is blended into the pressure sensitive adhesive or ii) the first epoxy curative is the pressure sensitive adhesive polymer.
2. The curable pressure sensitive adhesive tape according to claim 1 wherein the first epoxy curative is not encapsulated.
3. The curable pressure sensitive adhesive tape according to claim 1 or 2 wherein the first epoxy curative is blended into the pressure sensitive adhesive.
4. The curable pressure sensitive adhesive tape according to claim 1 or 2 wherein the first epoxy curative is the pressure sensitive adhesive.
5. The curable pressure sensitive adhesive tape according to claim 4 wherein the first epoxy curative is an adduct of a second epoxy curative and a second epoxy resin in a ratio of at least 2: 1 second epoxy curative to second epoxy resin.
6. The curable pressure sensitive adhesive tape according to claim 5 wherein the second epoxy curative is selected from the group consisting of polyamides, polyamines, polymercaptans, anhydrides, imidazoles, and combinations thereof.
7. The curable pressure sensitive adhesive tape according to claim 5 wherein the second epoxy curative is a polyamide or a polyamine.
8. The curable pressure sensitive adhesive tape according to any of claims 1-7 wherein the particles of encapsulated first epoxy resin comprise a core of first epoxy resin within a shell comprising an organic polymer.
9. The curable pressure sensitive adhesive tape according to claim 8 wherein the shell comprises a polymer selected from the group consisting of polyurea,
polyurethane, polymethylene urea, cured epoxy resin, and combinations thereof.
10. The curable pressure sensitive adhesive tape according to any of claims 8-9 wherein the particles of encapsulated first epoxy resin additionally comprise a layer of oil-in-water Pickering emulsifier particles borne on a surface of the shells.
11. A method of affixing substrates comprising:
a) bringing a curable pressure sensitive adhesive tape according to any of claims 1-10 into contact with a first substrate;
b) bringing the curable pressure sensitive adhesive tape into contact with a second substrate; and
c) heating the curable pressure sensitive adhesive tape to a curing temperature, which is a temperature sufficient to activate the particles of encapsulated first epoxy resin and cure the first epoxy resin.
12. The method according to claim 15, wherein the curing temperature is not more than 170 °C.
13. A construction comprising a first substrate bound to a second substrate by a layer of cured epoxy resin, wherein the layer of cured epoxy resin comprises shells comprising an organic polymer.
14. The construction according to claim 13 wherein the shells comprise a polymer selected from the group consisting of polyurea, polyurethane, polymethylene urea, cured epoxy resin, and combinations thereof.
15. The construction according to any of claims 13-14 wherein the shells comprise a layer of oil-in-water Pickering emulsifier particles borne on a surface of the shells.
PCT/IB2020/052743 2019-03-28 2020-03-24 Structural bonding tape with epoxide microcapsules WO2020194182A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US17/442,971 US20220195247A1 (en) 2019-03-28 2020-03-24 Structural bonding tape with epoxide microcapsules
CN202080025545.1A CN113646398A (en) 2019-03-28 2020-03-24 Structural adhesive tape with epoxide microcapsules
EP20715473.3A EP3947582A1 (en) 2019-03-28 2020-03-24 Structural bonding tape with epoxide microcapsules
JP2021557545A JP2022526958A (en) 2019-03-28 2020-03-24 Structural adhesive tape with epoxide microcapsules

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201962825291P 2019-03-28 2019-03-28
US62/825,291 2019-03-28

Publications (1)

Publication Number Publication Date
WO2020194182A1 true WO2020194182A1 (en) 2020-10-01

Family

ID=70057180

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2020/052743 WO2020194182A1 (en) 2019-03-28 2020-03-24 Structural bonding tape with epoxide microcapsules

Country Status (5)

Country Link
US (1) US20220195247A1 (en)
EP (1) EP3947582A1 (en)
JP (1) JP2022526958A (en)
CN (1) CN113646398A (en)
WO (1) WO2020194182A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220152574A1 (en) * 2019-03-28 2022-05-19 3M Innovative Properties Company Epoxide microcapsules with pickering emulsifiers

Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3018262A (en) 1957-05-01 1962-01-23 Shell Oil Co Curing polyepoxides with certain metal salts of inorganic acids
US3298998A (en) 1961-03-07 1967-01-17 Eastman Kodak Co Bisglycidyl ethers of bisphenols
US4522958A (en) 1983-09-06 1985-06-11 Ppg Industries, Inc. High-solids coating composition for improved rheology control containing chemically modified inorganic microparticles
US4536524A (en) 1981-04-21 1985-08-20 Capsulated Systems, Inc. Microencapsulated epoxy adhesive system
US5601761A (en) 1994-09-26 1997-02-11 The Dow Chemical Company Encapsulated active materials and method for preparing same
US6506494B2 (en) 1999-12-20 2003-01-14 3M Innovative Properties Company Ambient-temperature-stable, one-part curable epoxy adhesive
EP1373426A1 (en) 2001-03-29 2004-01-02 3M Innovative Properties Company Structural bonding tapes and articles containing the same
EP1530617A1 (en) 2002-08-19 2005-05-18 3M Innovative Properties Company Epoxy compositions having improved shelf life and articles containing the same
JP2006028254A (en) 2004-07-13 2006-02-02 Chukyo Yushi Kk Microcapsule and aqueous composition containing it
US7927514B2 (en) 2006-02-03 2011-04-19 Asahi Kasei Chemicals Corporation Microcapsule-based hardener for epoxy resin, masterbatch-based hardener composition for epoxy resin, one-part epoxy resin composition, and processed good
WO2011126702A2 (en) 2010-03-30 2011-10-13 Henkel Corporation Encapsulated curing agents
US8084519B2 (en) 2008-11-07 2011-12-27 The Yokohama Rubber Co., Ltd. Curing accelerator for epoxy resin composition, and one-pack type thermosetting epoxy resin composition
EP2700683A1 (en) 2012-08-23 2014-02-26 3M Innovative Properties Company Structural adhesive film
US20140272287A1 (en) 2013-03-15 2014-09-18 Prc-Desoto International Incorporated Energy curable sealants
US20150231588A1 (en) 2014-02-18 2015-08-20 Rohm And Haas Company Microcapsules
US20160068726A1 (en) * 2014-09-08 2016-03-10 Nd Industries, Inc. Adhesive composition and article including the same
CN105833811A (en) 2016-03-27 2016-08-10 华南理工大学 Double-capsule self-repairing epoxy coating and preparation method thereof

Patent Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3018262A (en) 1957-05-01 1962-01-23 Shell Oil Co Curing polyepoxides with certain metal salts of inorganic acids
US3298998A (en) 1961-03-07 1967-01-17 Eastman Kodak Co Bisglycidyl ethers of bisphenols
US4536524A (en) 1981-04-21 1985-08-20 Capsulated Systems, Inc. Microencapsulated epoxy adhesive system
US4522958A (en) 1983-09-06 1985-06-11 Ppg Industries, Inc. High-solids coating composition for improved rheology control containing chemically modified inorganic microparticles
US5601761A (en) 1994-09-26 1997-02-11 The Dow Chemical Company Encapsulated active materials and method for preparing same
US6506494B2 (en) 1999-12-20 2003-01-14 3M Innovative Properties Company Ambient-temperature-stable, one-part curable epoxy adhesive
EP1373426A1 (en) 2001-03-29 2004-01-02 3M Innovative Properties Company Structural bonding tapes and articles containing the same
EP1530617A1 (en) 2002-08-19 2005-05-18 3M Innovative Properties Company Epoxy compositions having improved shelf life and articles containing the same
JP2006028254A (en) 2004-07-13 2006-02-02 Chukyo Yushi Kk Microcapsule and aqueous composition containing it
US7927514B2 (en) 2006-02-03 2011-04-19 Asahi Kasei Chemicals Corporation Microcapsule-based hardener for epoxy resin, masterbatch-based hardener composition for epoxy resin, one-part epoxy resin composition, and processed good
US8084519B2 (en) 2008-11-07 2011-12-27 The Yokohama Rubber Co., Ltd. Curing accelerator for epoxy resin composition, and one-pack type thermosetting epoxy resin composition
WO2011126702A2 (en) 2010-03-30 2011-10-13 Henkel Corporation Encapsulated curing agents
EP2700683A1 (en) 2012-08-23 2014-02-26 3M Innovative Properties Company Structural adhesive film
US20140272287A1 (en) 2013-03-15 2014-09-18 Prc-Desoto International Incorporated Energy curable sealants
US20150231588A1 (en) 2014-02-18 2015-08-20 Rohm And Haas Company Microcapsules
US20160068726A1 (en) * 2014-09-08 2016-03-10 Nd Industries, Inc. Adhesive composition and article including the same
CN105833811A (en) 2016-03-27 2016-08-10 华南理工大学 Double-capsule self-repairing epoxy coating and preparation method thereof

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
"Epoxy Resins, Chemistry and Technology", 1988, MARCEL DEKKER, INC.
BINKS: "Particles as surfactants - similarities and differences", CURRENT OPINION IN COLLOID & INTERFACE SCIENCE, vol. 7, 2002, pages 21 - 41, XP002296320, DOI: 10.1016/S1359-0294(02)00008-0
CHEVALIER ET AL.: "Emulsions stabilized with solid nanoparticles: Pickering emulsions", COLLOIDS AND SURFACES A: PHYSICOCHEM. ENG. ASPECTS, vol. 439, 2013, pages 23 - 34, XP028764672, DOI: 10.1016/j.colsurfa.2013.02.054
LEENEVILLE: "Handbook of Epoxy Resins", 1967, MCGRAW-HILL BOOK CO.
PAUNOV: "Novel Method for Determining the Three-Phase Contact Angle of Colloid Particles Adsorbed at Air-Water and Oil-Water Interfaces", LANGMUIR, vol. 19, 2003, pages 7970 - 7976, XP002377711, DOI: 10.1021/la0347509

Also Published As

Publication number Publication date
EP3947582A1 (en) 2022-02-09
JP2022526958A (en) 2022-05-27
CN113646398A (en) 2021-11-12
US20220195247A1 (en) 2022-06-23

Similar Documents

Publication Publication Date Title
KR102052389B1 (en) Structural adhesive and bonding application thereof
JP6419579B2 (en) Waterborne epoxy resin dispersion and epoxy curing agent composition
CN102333819B (en) Epoxy adhesive compositions with high mechanical strength over a wide temperature range
US20220152574A1 (en) Epoxide microcapsules with pickering emulsifiers
JP5888349B2 (en) Adhesive composition and adhesive sheet using the same
TW201925339A (en) Curable composition based on fatty-acid modified epoxy resins and curing agents
JP6824986B2 (en) Acrylic / Epoxy Composites for Laminate Adhesive Applications
CN101681845A (en) Adhesive film and semiconductor device obtained with the same
US20220195247A1 (en) Structural bonding tape with epoxide microcapsules
JP2015533862A (en) Two-component (2K) bonding adhesive
JP6564588B2 (en) Porous monolith coating structure and manufacturing method thereof
TW201811856A (en) Curable adhesive compound and reactive adhesive tapes based thereon
JP3308347B2 (en) Microcapsule-type curing accelerator, epoxy resin composition containing the same, and cured product thereof
JP2005036095A (en) Adhesive composition
BR112017013725B1 (en) COATING COMPOSITION BASED ON ORGANIC SOLVENT AND COATED METALLIC SUBSTRATE
JP7280448B2 (en) Curable polymer compositions with improved oxygen barrier properties
EP3475332A1 (en) Curable compositions including a chromonic network, articles, and methods
WO2023176134A1 (en) Article, method for producing article, foamable adhesive sheet, and adhesive composition
KR20230130731A (en) Epoxy adhesive composition comprising elastomeric nanoparticles, and uses thereof
JPH02208386A (en) Adhesive composition
JPH06128545A (en) Adhesive composition
JP2006274060A (en) Method for producing epoxy resin composition
JP2012087229A (en) Epoxy resin composition

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 20715473

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2021557545

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2020715473

Country of ref document: EP

Effective date: 20211028